How to design a Dust Collection System

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Deciding if you want the collector(s) to be located inside or outside is an important decision and there are pros and cons with both. Indoor systems cost a lot less and do typically not need the expensive safety devices (No Return Valve, Spark Detection System, High Speed Abort Gate etc) and they are cheaper and much easier to install than an outside central system. However they also take up valuable room inside a building and handling the waste it collects is typically much more difficult.

Designing the duct  in any shop or factory is extremely important in order to make sure:   

1) There is proper suction to each  machine / fume arm / hood   

2) Waste material cannot build up in the duct and cause a fire hazard   

3) Velocity is kept correct in order to not waste energy but also not having material buildup in the main trunk-line    

The use   of blast gates is very popular in a lot of applications. Especially wood   shops tend to use a lot of blast gates as it saves a lot of energy - which means money!!    

Blast   gates are used in order to be able to install a dust collector that is small (cheaper to buy and operate) than the size of all machines connected to collector would typically require. For simplicity let's take a system with 10   different machines all with 4" connections in a wood shop with 5 people.   If the owner does not expect to use more than 5 machines at any given time   (and he does not plan to expand / change machines "any time soon") then the dust collector and the duct can be designed for 5 machines (2,000   CFM @ 4,500 FPM) instead of 10 machines (4,000 CFM @ 4,500 FPM). Even though   the difference here is only 2,000 CFM it is still a 50% saving vs the  "suction on all machines all the time" system and when a single machine   has 5,000 CRM or more requirement then using blast gates really makes a lot of financial sense if the machine is not used 100% of the time.     

There are different ways to put duct together and even though there is not a "right or wrong" there are ways some applications cannot be put together and there is a huge difference in how difficult and time consuming / costly it is. Below are the most common ways to install duct in a dust collection application:     

Using   Clamp-together duct - can be supplied for both dry and wet applications    

Using Flanged duct - can be supplied for both dry and wet applications    

Welding the duct   together - can be supplied for both dry and wet application   

Using Spiral duct    

Using Spiral duct with duroflanges    

The   clamp-together style duct has become more and more popular the higher the cost of installers has become. Also, many end-users see a benefit in being   able to install the duct themselves and just as important being able to making changes the their systems as they expand or change machines or move   machines around in their shop.    

Duct is typically fabricated out of either Galvanized Steel, Stainless Steel (304 and 316), Carbon Steel ("raw", painted or powder coated) or Aluminum all depending on the   application. For wood jobs Galvanized duct works perfectly (NEVER use plastic) while food applications often calls out for either SS304, SS316 or  Aluminum duct. At Industrial Solutions we will be happy to go over your application and quote the correct duct material for you. For high temp applications Stainless Steel and Carbon Steel is the best way to go.    

No matter which material the duct is made of there are different thicknesses (gauge) of the duct. Again, based upon the application it is important that   the correct gauge is used. Typically, standard gauge duct is thick enough but   in abrasive applications it is important that the duct is fabricated out of heavy gauge material in order to prolong the lifetime of the duct - in really abrasive applications it can even be useful to use "wearback" Elbows and/or coated Elbows.